The present invention relates to the detection of cracks and similar defects in stamped parts. More particularly, the present invention relates to the automated detection of cracks and similar defects in stamped parts during the stamping process.
Defects, particularly cracks, are a common problem inherent in component stamping. Such cracks, also commonly referred to as necking or elongation, may occur as a result of forming the material used to make a particular component. Defects in the material itself may also cause or contribute to the existence of cracks. Therefore, as used herein, the term crack shall encompass any type of separation in the material of a stamped component whether caused by the stamping (forming) process, by a deficiency in the physical structure of the material itself, or some combination thereof.
Cracks are problematic because they result in weakened areas that may cause a component to eventually fail during use. These cracks may also be undesirable for cosmetic reasons. Consequently, it is highly desirable that components containing cracks be discovered before being put to an end use or before their joining to other components of a larger assembly.
Discovery of such cracks is difficult, however, because detection is usually accomplished through visual observation of a component of interest. Unfortunately, such cracks are not particularly amenable to visual detection for various reasons. For example, such cracks may, at least initially, be rather small in size. There is generally also no color change or other obvious variation between a crack and the surrounding component material to call attention to the defect. Further, the responsibility for crack detection often falls on the shoulders of a machine operator or another person tasked with such duties—and often must be accomplished very quickly, such as within a single machine cycle.
Additionally, it can be understood by one skilled in the art that, with respect to certain stamping processes such as, for example, a transfer press process, off-line (end of process) inspection may result in excessive scrap. That is, if a crack is being produced early in the stamping process, and inspection cannot be accomplished until the end of the process, a number of additional defective components will have been produced prior to the first defective component reaching the inspection station. Offline component inspection may also add to overall manufacturing cycle time.
Therefore, what is needed is a system and method for automatically detecting cracks in stamped components, preferably within the physical confines and operating parameters of related stamping equipment. A system and method of the present invention satisfies this need.